Appearances to the mind are of four kinds. Things either are what they appear to be; or they neither are, nor appear to be; or they are, and do not appear to be; or they are not, and yet appear to be. Rightly to aim in all these cases is the wise man’s task.

Epictetus (c. 55-c. 135 AD) Greek (Phrygian) Stoic philosopher [Ἐπίκτητος, Epíktētos]

The Discourses (c. AD 101-108)